I kinda look at the 45/70 much in the same way as Lloyd, in that it’s just a bigger 45 caliber – no more, no less. Now granted, it can throw huge chunks of lead at close to warp speed downrange meaning that you’ll get lots of penetration – more so than a 45 Colt or 454 Casull, but it’s still 0.458 in diameter – better than 0.452 but still a 45.
Bigger normally is better and in this case the 500 Linebaughs & 50 Alaskans at 0.512 diameter is the better killing machine by far and they normally will completely penetrate most anything within North America end to end.
For the cost – the BFR 45/70 or maybe that Ruger is a whole lot less money than the Linebaugh or Alaskan and will definitely do what needs done. And like one poster advised – you won’t be fumbling any cartridges when reloading those bad boys.
With that length cylinder and loaded with 500+ grains of lead - it's on the heavy side for an ole man - you young studs can take it in stride. It's a great revolver but not for everyone.
I’ve got a 500 Linebaugh Max for no other reason than I wanted it and it was offered at a price I could afford. I shoot the snot out of it but I keep most of my shooting at or around the 1,000fps mark with a 440 grain HC and it’s very enjoyable and accurate. If you want - you can approach the 1,600fps mark with a 440 grain HC in an attempt to break your wrist but the penetration won’t be but an inch or two more than if you kept the velocity down to the 1,250/1,300fps area and experience only mild discomfort.